Process for increasing the softness of base webs and products made therefrom

ABSTRACT

A process for increasing the tactile properties of a base web without adversely effecting the strength of the web is disclosed. In one embodiment, the process includes the steps of placing a base web between a first moving conveyor and a second moving conveyor. The conveyors are then wrapped around a shear-inducing roll which creates shear forces that act upon the base web. The shear forces disrupt the web, increasing the softness and decreasing the stiffness of the web. The shear-inducing roll typically has a relatively small diameter. In some applications, more than one shear-inducing roll may be incorporated into the system. Base webs made according to the present invention have been found to have improved void-volume and fuzz-on-edge properties.

RELATED APPLICATIONS

[0001] The present application is based on a Provisional Applicationfiled on May 12, 2000 having U.S. Application No. 60/204,083.

BACKGROUND OF THE INVENTION

[0002] Products made from base webs such as bath tissues, facialtissues, paper towels, industrial wipers, foodservice wipers, napkins,medical pads, and other similar products are designed to include severalimportant properties. For example, the products should have a soft feeland, for most applications, should be highly absorbent. The productsshould also have good stretch characteristics and should resist tearing.Further, the products should also have good strength characteristics,should be abrasion resistant, and should not deteriorate in theenvironment in which they are used.

[0003] In the past, many attempts have been made to enhance and increasecertain physical properties of such products. Unfortunately, however,when steps are taken to increase one property of these products, othercharacteristics of the products may be adversely affected. For instance,the softness of nonwoven products, such as various paper products, canbe increased by several different methods, such as by selecting aparticular fiber type, or by reducing cellulosic fiber bonding withinthe product. Increasing softness according to one of the above methods,however, may adversely affect the strength of the product. Conversely,steps normally taken to increase the strength of a fibrous web typicallyhave an adverse impact upon the softness, the stiffness or theabsorbency of the web.

[0004] The present invention is directed to improvements in base websand to improvements in processes for making the webs in a manner thatoptimizes the physical properties of the webs. In particular, thepresent invention is directed to a process for improving the tactileproperties, such as softness and stiffness, of base webs withoutseverely diminishing the strength of the webs.

SUMMARY OF THE INVENTION

[0005] As stated above, the present invention is directed to furtherimprovements in prior art constructions and methods, which are achievedby providing a process for producing base webs, namely base webscontaining pulp fibers. The process includes the steps of first forminga base web. The base web can be made from various fibers and can beconstructed in various ways. For instance, the base web can contain pulpfibers and/or staple fibers. Further, the base web can be formed in awet-lay process, an air-forming process, or the like.

[0006] Once the base web is formed, the web is subjected to shear forcessufficient to improve the softness properties of the web. For instance,in one embodiment the web is placed in between a first moving conveyorand a second moving conveyor. The first and second moving conveyors arethen guided around a shear-inducing roll while the base web ispositioned in between the conveyors. The conveyors are sufficientlywrapped around the shear-inducing roll and are placed under a sufficientamount of tension so as to create shear forces that act upon the baseweb. The shear forces disrupt the web increasing the softness anddecreasing the stiffness of the web. Of particular advantage, it hasbeen discovered that the softness of the web is increased withoutsubstantially reducing the strength of the web. More particularly, ithas been discovered that the process shifts the normal strength-softnesscurve so as to create webs having unique softness and strengthproperties.

[0007] When guided around the shear-inducing roll, the base web shouldhave a moisture content of less than about 10%, particularly less thanabout 5%,and more particularly less than about 2%.

[0008] The shear-inducing roll can rotate or can be a stationary device.For most applications, the shear-inducing roll should have a smalleffective diameter, such as less than about 10 inches, particularly lessthan about 7 inches and more particularly from about 2 inches to about 6inches. For most applications, the conveyors should be wrapped aroundthe shear-inducing roll at least 30° and particularly from about 50° toabout 270°. Further, the amount of tension placed upon the conveyorswhen wrapped around the shear-inducing roll should be at least 5 poundsper linear inch and particularly from about 10 pounds per linear inch toabout 50 pounds per linear inch.

[0009] Various types of base webs can be processed according to thepresent invention. For example, in one embodiment, the base web can be astratified web including a middle layer positioned between a first outerlayer and a second outer layer. In one embodiment, the outer layers canhave a tensile strength greater than the middle layer. For example, theouter layers can be made from softwood fibers, while the middle layercan be made from hardwood fibers.

[0010] Alternatively, the middle layer can have a tensile strengthgreater than the outer layers. It has been discovered by the presentinventors that various unique products can be formed when usingstratified base webs as described above.

[0011] The present inventors have discovered that the process of thepresent invention produces unique products having improved softnesscharacteristics. In particular, it has been discovered that base websmade according to the present invention have improved void-volumeproperties and fuzz-on-edge properties. In this regard, the presentinvention is directed to a paper product that includes a nonwoven baseweb containing pulp fibers. The base web has a void volume greater than12 g/g. Further, base webs made according to the present invention canhave the above void-volume levels even at basis weights greater than 20gsm, particularly greater than 25 gsm, and more particularly greaterthan 30 gsm.

[0012] The void volume properties of base webs made according to thepresent invention can also be improved without substantially decreasingthe tensile strength of the webs. For example, base webs having a voidvolume greater than 12 g/g, can also have a geometric mean tensilestrength of greater than about 170 g/in.

[0013] Besides dramatically improving the void volume of base webs, theprocess of the present invention also improves the fuzz-on-edgeproperties of the base web. In general, the fuzz-on-edge test measuresthe amount of fibers present on the surface of the web that aregenerally aligned in the z-direction. The degree of “fuzziness” of a webhas also been measured in a test referred to as a “perimeter per edgelength” test as described in European Application No. 0 539 703 which isincorporated herein by reference. A greater fuzz-on-edge generallyindicates a softer web. It has been found that base webs made accordingto the present invention can have a fuzz-on-edge in an amount greaterthan 2.2 mm/mm, and particularly greater than 2.5 mm/mm.

[0014] Base webs having the above properties can be single-ply base websmade according to various processes. For example, in one embodiment, thebase web can be an uncreped, through-air-dried base web. Alternatively,the base web can be dried on a yankee dryer and creped.

[0015] Base webs processed according to the present invention can havevarious applications and uses. In one particular embodiment, base websmade according to the present invention can be single ply base websparticularly well suited for use as a bath tissue. Beside bath tissues,however, the base webs can also be used and incorporated into facialtissues, paper towels, industrial wipers, foodservice wipers, napkins,medical pads, diapers, feminine-hygiene products, and other similarproducts.

[0016] Other features and aspects of the present invention are discussedin greater detail below. dr

BRIEF DESCRIPTION OF THE DRAWINGS

[0017] A full and enabling disclosure of the present invention,including the best mode thereof to one of ordinary skill in the art, isset forth more particularly in the remainder of the specification,including reference to the accompanying figures in which:

[0018]FIG. 1 is a schematic diagram of a fibrous web forming machineillustrating one embodiment for forming a base web having multiplelayers in accordance with the present invention;

[0019]FIG. 2 is a schematic diagram of a fibrous web forming machinethat crepes one side of the web;

[0020]FIG. 3 is a perspective view with cut away portions of a fibrousweb forming machine that includes a through-air dryer for removingmoisture from the web;

[0021]FIG. 4 is a schematic diagram of one embodiment for a process forimproving the tactile properties of a formed base web in accordance withthe present invention;

[0022]FIG. 5 is a schematic diagram of an alternative embodiment of aprocess for improving the tactile properties of a formed base web madein accordance with the present invention;

[0023]FIG. 6 is a schematic diagram of another alternative embodiment ofa process for improving the tactile properties of a formed base web madein accordance with the present invention;

[0024]FIG. 7 is a schematic diagram of a further alternative embodimentof a process for improving the tactile properties of a formed base webmade in accordance with the present invention;

[0025] FIGS. 8 and 9 are the results obtained in the example describedbelow;

[0026]FIG. 10 is a perspective view of the fixture used to conduct thefuzz-on-edge test as described below; and

[0027]FIG. 11 is a diagrammatical view showing the measurements takenduring the fuzz-on-edge test.

[0028] Repeat use of reference characters in the present specificationand drawings is intended to represent same or analogous features orelements of the present invention.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS

[0029] It is to be understood by one of ordinary skill in the art thatthe present discussion is a description of exemplary embodiments only,and is not intended as limiting the broader aspects of the presentinvention, which broader aspects are embodied in the exemplaryconstruction.

[0030] In general, the present invention is directed to a process forimproving the tactile properties of base webs without a subsequentsubstantial loss in tensile strength. The present invention is alsodirected to webs made from the process. In particular, the process ofthe present invention is well suited to increasing the softness anddecreasing the stiffness of base webs, such as webs containing pulpfibers. Further, in some applications, the caliper of a web can bereduced while still gaining all of the above advantages.

[0031] Generally speaking, the process of the present invention includesthe step of subjecting a previously formed base web to a shearing forcein an amount sufficient to improve the softness of the web. Forinstance, the base web can be subjected to a shearing force in an amountsufficient to improve the void volume of the web and the fuzz-on-edgeproperties of the web.

[0032] In accordance with the present invention, a shearing force can beapplied to the web by placing the web between a pair of movingconveyors. As used herein, a conveyor is intended to refer to a flexiblesheet, such as a wire, a fabric, a felt, and the like. Once the base webis placed in between the moving conveyors, a speed differential iscreated between the two conveyors which applies a shearing force to theweb. For example, in one embodiment, the conveyors can be guided aroundat least one shear-inducing element, such as a roll, while the web issandwiched between the two conveyors. The shear-inducing element canrotate or can be stationary and typically has a small effectivediameter, such as less than about 10 inches.

[0033] The moving conveyors have a sufficient amount of wrap around theshear-inducing element and are placed under sufficient tension to createshear forces that act upon the base web. Specifically, passing theconveyors over the shear-inducing element causes a speed differential inthe conveyors which creates a shearing force that breaks bonds withinthe web or otherwise disrupts fiber entanglement within the web, wherethe web is weakest. Through this process, the softness of the webincreases while the stiffness of the web is reduced. Unexpectedly, thepresent inventors have discovered that this softening occurs withsubstantially less loss of tensile strength than would be expected atthe softness levels obtained.

[0034] Base webs that may be used in the process of the presentinvention can vary depending upon the particular application. Ingeneral, any suitable base web may be used in the process in order toimprove the tactile properties of the web. Further, the webs can be madefrom any suitable type of fiber.

[0035] For example, the manner in which the base web of the presentinvention is formed may vary depending upon the particular application.In one embodiment, the web can contain pulp fibers and can be formed ina wet-lay process according to conventional paper making techniques. Ina wet-lay process, the fiber furnish is combined with water to form anaqueous suspension. The aqueous suspension is spread onto a wire or feltand dried to form the web.

[0036] Alternatively, the base web of the present invention can be airformed. In this embodiment, air is used to transport the fibers and forma web. Air-forming processes are typically capable of processing longerfibers than most wet-lay processes, which may provide an advantage insome applications.

[0037] Referring to FIG. 2, one embodiment of a process for producing abase web that may be used in accordance with the present invention isillustrated. The process illustrated in the figure depicts a wet-layprocess, although, as described above, other techniques for forming thebase web of the present invention may be used.

[0038] As shown in FIG. 2, the web-forming system includes a headbox 10for receiving an aqueous suspension of fibers. Headbox 10 spreads theaqueous suspension of fibers onto a forming fabric 26 that is supportedand driven by a plurality of guide rolls 34. A vacuum box 36 is disposedbeneath forming fabric 26 and is adapted to remove water from the fiberfurnish to assist in forming a web.

[0039] From forming fabric 26, a formed web 38 is transferred to asecond fabric 40, which may be either a wire or a felt. Fabric 40 issupported for movement around a continuous path by a plurality of guiderolls 42. Also included is a pick up roll 44 designed to facilitatetransfer of web 38 from fabric 26 to fabric 40. The speed at whichfabric 40 can be driven is approximately the same speed at which fabric26 is driven so that movement of web 38 through the system isconsistent. Alternatively, the two fabrics can be run at differentspeeds, such as in a rush transfer process, in order to increase thebulk of the webs or for some other purpose.

[0040] From fabric 40, web 38, in this embodiment, is pressed onto thesurface of a rotatable heated dryer drum 46, such as a Yankee dryer, bya press roll 43. Web 38 is lightly pressed into engagement with thesurface of dryer drum 46 to which it adheres, due to its moisturecontent and its preference for the smoother of the two surfaces. As web38 is carried through a portion of the rotational path of the dryersurface, heat is imparted to the web causing most of the moisturecontained within the web to be evaporated.

[0041] Web 38 is then removed from dryer drum 46 by a creping blade 47.Creping web 38 as it is formed reduces internal bonding within the weband increases softness.

[0042] In an alternative embodiment, instead of wet pressing the baseweb 38 onto a dryer drum and creping the web, the web can be through-airdried. A through-air dryer accomplishes the removal of moisture from thebase web by passing air through the web without applying any mechanicalpressure.

[0043] For example, referring to FIG. 3, an alternative embodiment forforming a base web for use in the process of the present inventioncontaining a through-air dryer is illustrated. As shown, a diluteaqueous suspension of fibers is supplied by a headbox 10 and depositedvia a sluice 11 in uniform dispersion onto a forming fabric 26 in orderto form a base web 38.

[0044] Once deposited onto the forming fabric 26, water is removed fromthe web 38 by combinations of gravity, centrifugal force and vacuumsuction depending upon the forming configuration. As shown in thisembodiment, and similar to FIG. 2, a vacuum box 36 can be disposedbeneath the forming fabric 26 for removing water and facilitatingformation of the web 38.

[0045] From the forming fabric 26, the base web 38 is then transferredto a second fabric 40. The second fabric 40 carries the web through athrough-air drying apparatus 50. The through-air dryer 50 dries the baseweb 38 without applying a compressive force in order to maximize bulk.For example, as shown in FIG. 3, the through-air drying apparatus 50includes an outer rotatable cylinder 52 with perforations 54 incombination with an outer hood 56. Specifically, the fabric 40 carriesthe web 38 over the upper portion of the through air drying apparatusouter cylinder 52. Heated air is drawn through perforations 54 whichcontacts the web 38 and removes moisture. In one embodiment, thetemperature of the heated air forced through the perforations 54 can befrom about 170° F. to about 500° F.

[0046] After the base web 38 is formed, such as through one of theprocesses illustrated in FIGS. 2 and 3 or any other suitable process,the web is placed between a pair of moving conveyors and pressed arounda shear-inducing element in accordance with the present invention. Forinstance, one embodiment of a process for improving the tactileproperties of a base web in accordance with the present invention isillustrated in FIG. 4. As shown, the base web 38 is supplied between afirst moving conveyor 60 and a second moving conveyor 62. The speed atwhich the conveyors 60 and 62 are moving is generally not critical tothe present invention. For most commercial applications, the conveyorscan be moving at a speed of from about 1,000 feet per minute to about6,000 feet per minute.

[0047] Once positioned in between the first conveyor 60 and the secondconveyor 62, the base web and the conveyors are guided around ashear-inducing roll 64 by a pair of support rolls 66 and 68. Inaccordance with the present invention, the conveyors 60 and 62 areplaced under tension and are wrapped around the shear-inducing roll 64in amounts sufficient to create shear forces that act upon the base web38. In particular, when the conveyors are passed over the shear-inducingroll, a speed differential develops in the conveyors.

[0048] Due to the interaction between the surfaces of the conveyors andthe contacting surface of the web, the speed differential of theconveyors can be translated into a speed differential between the twoweb surfaces. Factors which can affect the web surface/conveyor surfaceinteraction can include but are not limited to, for example, thecoefficient of friction at the conveyor surfaces, the tension of theconveyors, and the moisture content of the web. A speed differentialbetween the two web surfaces can create shearing forces which act uponthe base web. The shearing forces can break bonds within the web wherethe web is weakest, which subsequently increases the softness anddecreases the stiffness of the web.

[0049] Further, the present inventors have discovered that theseimprovements are realized without a significant decrease in tensilestrength as normally occurs in other processes designed to increasesoftness.

[0050] The inventors have also unexpectedly discovered that the processof the present invention produces a web with distinct properties.Specifically, the web produced by the present invention shows improvedcharacteristics in terms of both void volume and fuzz-on-edgeproperties. Of particular significance, it is believed that void-volumeand fuzz-on-edge characteristics are completely unrelated properties.Thus, it is believed that the shearing force applied to the base webaccording to the present invention is improving two unrelated propertiesthat translate into greater softness.

[0051] In general, void volume is a measure of the volume of liquidwhich can be contained within a sheet. As used herein, void volume isdetermined according to the POROFIL test described in EXAMPLE 2 below.It is generally held that an increase in void volume becomes moredifficult as basis weight of the sheet increases, due primarily tosurface effects of higher basis weight webs. The webs produced by thepresent invention have unexpectedly been found to have a void volumegreater than 11.5 g/g and particularly greater than 12 g/g. This resultis even more unexpected due to the relatively high basis weight tissuewebs which can be produced in certain embodiments of the presentinvention. For example, in one embodiment of the present invention,single-ply webs can be produced having a basis weight of greater thanabout 20 gsm and a void volume of greater than 11.5 g/g. Morespecifically, a single-ply web, suitable as a bath tissue, can beproduced by the present invention that can have a basis weight of morethan about 30 gsm and a void volume of greater than about 12.0 g/g.

[0052] An increase in void volume has been correlated with an increasein softness of a sheet, as in, for example, U.S. Pat. No. 5,494,554 andEP 0 613 979 A1 both to Edwards et al., both of which are incorporatedin their entirety by reference thereto.

[0053] As stated above, besides void volume, the process of the presentinvention also increases the fuzz-on-edge properties of the base web. Asused herein, a fuzz-on-edge test is a test that generally measures theamount of fibers present on the surface of the base web that protrudefrom the sheet. As used herein, the fuzz-on-edge is measured accordingto the test as described in EXAMPLE 2 below. The greater thefuzz-on-edge of a base web, the softer the base web feels. Inparticular, the fuzz-on-edge corresponds to a greater number of fiberson the surface of the web in the z-direction which provides a “fuzzy”soft feel.

[0054] Base webs made according to the present invention can have afuzz-on-edge in an amount greater than about 2.0 mm/mm, particularlygreater than 2.2 mm/mm, and more particularly greater than about 2.5mm/mm.

[0055] Referring back to FIG. 4, when fed around the shear-inducing roll64, base web 38 should generally have a low moisture content. Forexample, the base web 38 should have a moisture content of less thanabout 10% by weight, particularly less than about 5% by weight, and moreparticularly less than about 2% by weight.

[0056] As shown in FIG. 4, the shear-inducing roll 64 can be a rotatingroll having a relatively small diameter. In other embodiments, however,the shear-inducing roll can be a stationary roll. The effective diameterof the shear-inducing roll, for most applications, should be less thanabout 10 inches, particularly less than about 7 inches, and moreparticularly from about 2 inches to about six inches.

[0057] The amount that conveyors 60 and 62 are wrapped around theshear-inducing roll 64 can vary depending upon the particularapplication and the amount of shear that is desired to be exerted on theweb. For most applications, however, the conveyors should be wrappedaround the shear-inducing roll in an amount from about 30° to about270°, particularly from about 50° to about 200°, and more particularlyfrom about 80° to about 180°. In the embodiment illustrated in FIG. 4,the amount of wrap placed around the shear-inducing roll can be adjustedby adjusting the position of either the shear-inducing roll 64 or thesupport rolls 66 and 68. For instance, by moving the shear-inducing roll64 down closer to the support rolls 66 and 68, the conveyors will wraparound the shear-inducing roll 64 a lesser extent.

[0058] As described above, besides the amount of wrap that is placedaround the shear-inducing roll, the amount of tension placed upon theconveyors 60 and 62 can also have an impact on the amount of shear thatis exerted on the base web 38. The amount of tension placed upon theconveyors will depend upon the particular application. For mostapplications, however, the conveyors 60 and 62 should be placed undertension in an amount from about 5 pounds per linear inch to about 90pounds per linear inch, particularly from about 10 pounds per linearinch to about 50 pounds per linear inch, and more particularly fromabout 30 pounds per linear inch to about 40 pounds per linear inch.

[0059] As described above, when the conveyors 60 and 62 are wrappedaround the shear-inducing roll 64 under a sufficient amount of tension,a surface speed differential develops between the two surfaces of theweb that creates the shear forces. For most applications, the speeddifferential should be from about 0.5% to about 5%, and particularlyfrom about 1% to about 3% with conveyor on the outside moving fasterthan the conveyor contacting the roll.

[0060] After the base web 38 has been guided around the shear-inducingroll 64, the web can be further processed as desired. In one embodiment,as shown in FIG. 4, the web can be collected onto a reel 69 for laterpackaging.

[0061] During this process, the tactile properties of the base web canbe greatly enhanced, without seriously affecting the strength of theweb. Further, in some applications, it has been discovered that thecaliper of the web can be dramatically reduced. Caliper reductionwithout adversely affecting other properties of the web is beneficial inthat more material can be placed upon reel 69, which provides variousprocessing benefits. The amount of caliper reduction for a given baseweb will depend upon the application. In general, the caliper of a sheetis reduced by the pressure (P) applied to it by the tension (T) of thefabrics and the radius (R) of the roll, governed by the equation P=T/R.

[0062] The amount of caliper reduction achieved can be controlled byadjusting numerous variables. The number of shear-inducing rolls, theradius of the rolls, dwell time within the nip, nip pressure, conveyortype and base sheet structure all have an impact on the amount ofcaliper the process can remove. Percent caliper reduction increases withan increase in dwell time, number of rolls, nip pressure, and fabricmesh. Dwell time can be affected by the secondary variables of speed andwrap angle. Nip pressure can be varied by the secondary variables offabric tension and roll diameter. Fabric mesh can be varied by usingfabrics of differing knuckle surfaces. Thus far, it has been discoveredthat the caliper of a base web can be decreased up to as much as 75%,and particularly from about 20% to about 70%.

[0063] In the embodiment illustrated in FIG. 4, the system includes asingle shear-inducing roll 64. In other embodiments, however, moreshear-inducing rolls can be used. For instance, in other embodiments,the conveyors can be wrapped around two shear-inducing rolls, threeshear-inducing rolls, and even up to ten shear-inducing rolls. Referringto FIG. 5, an alternative embodiment of the present invention isillustrated that includes five shear-inducing rolls.

[0064] As shown, the base web 38 is fed between the first conveyor 60and the second conveyor 62 and is then wrapped around support rolls 70and 72 and shear-inducing rolls 74, 76, 78, 80, and 82. In general,using more shear-inducing rolls can create more shear that is exerted onthe base web. Although the shear-inducing rolls are illustrated ashaving approximately equal diameters, alternative embodiments may bedesired with some or all of the shear-inducing rolls having diameterswhich are unequal to the others.

[0065] When using more than one shear-inducing roll, the total wrap ofthe conveyors around all of the shear-inducing rolls should be at least90° for most embodiments. More particularly, especially when using morethan two shear-inducing rolls, the total wrap should be greater than100°, and particularly greater than 120°. The total wrap, however, canincrease or decrease depending upon increasing or decreasing the numberof shear-inducing rolls respectively.

[0066] Further embodiments of systems made in accordance with thepresent invention are illustrated in FIGS. 6 and 7. The systemillustrated in FIG. 6 includes a single shear-inducing roll 100. Asshown, conveyors 60 and 62 are guided around the shear-inducing roll 100by support rolls 102, 104, 106 and 108.

[0067] The system illustrated in FIG. 7 also includes a singleshear-inducing roll 110. It should be understood, however, that moreshear-inducing rolls can be included in any of the systems illustrated.As shown in FIG. 7, shear-inducing roll 110 is supported by a backingroll 112. In order to facilitate the amount of wrap aroundshear-inducing roll 110, the system further includes support rolls 114and 116.

[0068] As stated above, base webs processed according to the presentinvention can be made from various materials and fibers. For instance,the base web can be made from pulp fibers, other natural fibers,synthetic fibers, and the like.

[0069] For instance, in one embodiment of the present invention, thebase web contains pulp fibers either alone or in combination with othertypes of fibers. The pulp fibers used in forming the web can be, forinstance, softwood fibers having an average fiber length of greater than1 mm and particularly from about 2 to 5 mm based on a length weightedaverage. Such fibers can include Northern softwood kraft fibers.Secondary fibers obtained from recycled materials may also be used.

[0070] In one embodiment, staple fibers (and filaments) can be added tothe web to increase the strength, bulk, softness and smoothness of theweb. Staple fibers can include, for instance, polyolefin fibers,polyester fibers, nylon fibers, polyvinyl acetate fibers, cotton fibers,rayon fibers, non-woody plant fibers, and mixtures thereof. In general,staple fibers are typically longer than pulp fibers. For instance,staple fibers typically have fiber lengths of 5 mm and greater.

[0071] The staple fibers added to the base web can also includebicomponent fibers. Bicomponent fibers are fibers that can contain twomaterials such as, but not limited to, in a side by side arrangement orin a core and sheath arrangement. In a core and sheath fiber, generallythe sheath polymer has a lower melting temperature than the corepolymer. For instance, the core polymer, in one embodiment, can be nylonor a polyester, while the sheath polymer can be a polyolefin such aspolyethylene or polypropylene. Such commercially available bicomponentfibers include CELBOND fibers marketed by the Hoechst Celanese Company.

[0072] The staple fibers used in the base web of the present inventioncan also be curled or crimped. The fibers can be curled or crimped, forinstance, by adding a chemical agent to the fibers or subjecting thefibers to a mechanical process. Curled or crimped fibers may create moreentanglement and void volume within the web and further increase theamount of fibers oriented in the Z direction as well as increase webstrength properties.

[0073] In one embodiment, when forming paper products containing pulpfibers, the staple fibers can be added to the web in an amount fromabout 5% to about 30% by weight and particularly from about 5% to about20% by weight.

[0074] When the base web of the present invention is not used to makepaper products, but instead is incorporated into other products such asdiapers, feminine-hygiene products, garments, personal-care products,and various other products, the base web can be made from greateramounts of staple fibers.

[0075] Besides pulp fibers and staple fibers, thermomechanical pulp canalso be added to the base web. Thermomechanical pulp, as is known to oneskilled in the art, refers to pulp that is not cooked during the pulpingprocess to the same extent as conventional pulps. Thermomechanical pulptends to contain stiff fibers and has higher levels of lignin.Thermomechanical pulp can be added to the base web of the presentinvention in order to create an open pore structure, thus increasingbulk and absorbency and improving resistance to wet collapse.

[0076] When present, the thermomechanical pulp can be added to the baseweb in an amount from about 10% to about 30% by weight. When usingthermomechanical pulp, a wetting agent is also preferably added duringformation of the web. The wetting agent can be added in an amount lessthan about 1% and, in one embodiment, can be a sulphonated glycol.

[0077] In some embodiments, it is desirable to limit the amount of innerfiber-to-fiber bond strength. In this regard, the fiber furnish used toform the base web can be treated with a chemical debonding agent. Thedebonding agent can be added to the fiber slurry during the pulpingprocess or can be added directly into the headbox. Suitable debondingagents that may be used in the present invention include cationicdebonding agents such as fatty dialkyl quaternary amine salts, monofatty alkyl tertiary amine salts, primary amine salts, imidazolinequaternary salts, and unsaturated fatty alkyl amine salts. Othersuitable debonding agents are disclosed in U.S. Pat. No. 5,529,665 toKaun which is incorporated herein by reference.

[0078] In one embodiment, the debonding agent used in the process of thepresent invention can be an organic quaternary ammonium chloride. Inthis embodiment, the debonding agent can be added to the fiber slurry inan amount from about 0.1% to about 1% by weight, based on the totalweight of fibers present within the slurry.

[0079] The base web of the present invention may also have a multi-layerconstruction. For instance, the web can be made from a stratified fiberfurnish having at least three principal layers.

[0080] It has been discovered by the present inventors that variousunique products can be formed when processing a stratified base webaccording to the present invention. For example, as described above, theprocess of the present invention causes web disruption in the area ofthe web that is weakest. Consequently, one particular embodiment of thepresent invention is directed to using a stratified base web thatcontains weak outer layers and a strong center layer. Upon exposure tothe shear forces created through the process of the present invention,bonds are broken on the outer surface of the sheet, while the strengthof the center layer is maintained. The net effect is a base web havingimproved softness and stiffness with minimal strength loss.

[0081] In an alternative embodiment, a stratified base web can be usedthat has outer layers having a greater tensile strength than a middlelayer. In this embodiment, upon exposure to the shear forces created bythe process of the present invention, bonds in the middle layer fail butthe integrity of the outer layers is maintained. The resulting sheetsimulates, in some respects, the properties of a two-ply sheet.

[0082] There are various methods available for creating stratified basewebs. For instance, referring to FIG. 1, one embodiment of a device forforming a multi-layered stratified fiber furnish is illustrated. Asshown, a three-layered headbox generally 10 may include an upper headboxwall 12 and a lower headbox wall 14. Headbox 10 may further include afirst divider 16 and a second divider 18, which separate three fiberstock layers. Each of the fiber layers 24, 20, and 22 comprise a diluteaqueous suspension of fibers.

[0083] An endless traveling forming fabric 26, suitably supported anddriven by rolls 28 and 30, receives the layered stock issuing fromheadbox 10. Once retained on fabric 26, the layered fiber suspensionpasses water through the fabric as shown by the arrows 32. Water removalis achieved by combinations of gravity, centrifugal force and vacuumsuction depending on the forming configuration.

[0084] Forming multi-layered webs is also described and disclosed inU.S. Pat. No. 5,129,988 to Farrington, Jr. and in U.S. Pat. No.5,494,554 to Edwards, et al., which are both incorporated herein byreference.

[0085] In forming stratified base webs, various methods and techniquesare available for creating layers that have different tensile strengths.For example, debonding agents can be used as described above in order toalter the strength of a particular layer.

[0086] Alternatively, different fiber furnishes can be used for eachlayer in order to create a layer with desired characteristics. Forexample, in one embodiment, softwood fibers can be incorporated into alayer for providing tensile strength, while hardwood fibers can beincorporated into an adjacent layer for creating a weaker tensilestrength layer.

[0087] More particularly, it is known that layers containing hardwoodfibers typically have a lower tensile strength than layers containingsoftwood fibers. Hardwood fibers have a relatively short fiber length.For instance, hardwood fibers can have a length of less than about 2millimeters and particularly less than about 1.5 millimeters.

[0088] In one embodiment, the hardwood fibers incorporated into a layerof the base web include eucalyptus fibers. Eucalyptus fibers typicallyhave a length of from about 0.8 millimeters to about 1.2 millimeters.When added to the web, eucalyptus fibers increase the softness, enhancethe brightness, increase the opacity, and increase the wicking abilityof the web.

[0089] Besides eucalyptus fibers, other hardwood fibers may also beincorporated into the base web of the present invention. Such fibersinclude, for instance, maple fibers, birch fibers and possibly recycledhardwood fibers.

[0090] In general, the above-described hardwood fibers can be present inthe base web in any suitable amount. For example, the fibers cancomprise from about 5% to about 100% by weight of one layer of the web.

[0091] The hardwood fibers can be present within the lower tensilestrength layer of the web either alone or in combination with otherfibers, such as other cellulosic fibers. For instance, the hardwoodfibers can be combined with softwood fibers, with superabsorbentmaterials, and with thermomechanical pulp.

[0092] As described above, stronger tensile strength layers can beformed using softwood fibers, especially when adjacent weaker tensilestrength layers are made from hardwood fibers. The softwood fibers canbe present alone or in combination with other fibers. For instance, insome embodiments, staple fibers, such as synthetic fibers, can becombined with the softwood fibers.

[0093] The weight of each layer of a stratified base web in relation tothe total weight of the web is generally not critical. In mostembodiments, however, the weight of each outer layer will be from about15% to about 40% of the total weight of the web, and particularly fromabout 25% to about 35% of the weight of the web.

[0094] The basis weight of base webs made according to the presentinvention can vary depending upon the particular application. Ingeneral, for most applications, the basis weight can be from about 5pounds per 2,880 square feet (ream) (8.5 gsm) to about 80 pounds perream (136 gsm), and particularly from about 6 pounds per ream (10.2 gsm)to about 30 pounds per ream (51 gsm). In one embodiment, the presentinvention can be used to construct a single ply bath tissue having abasis weight of from about 20 gsm to about 40 gsm. Some other uses ofthe base webs include use as a wiping product, as a napkin, as a medicalpad, as an absorbent layer in a laminate product, as a placemat, as adrop cloth, as a cover material, as a facial tissue, or for any productthat requires liquid absorbency.

[0095] The present invention may be better understood with reference tothe following examples.

EXAMPLE 1

[0096] In this experiment, paper webs were produced, placed between twofabrics, and then guided around at least one shear-inducing roll. Moreparticularly, stratified webs were tested which included three layers.The two outer layers of the web were made from eucalyptus fibers. Themiddle layer, however, contained softwood fibers. The webs were producedusing a through-air dryer similar to the system illustrated in FIG. 3.The base webs had an average basis weight of about 18.9 lbs/ream.

[0097] Once formed, the webs were then placed in between a pair offabrics and guided around at least one shear-inducing roll, similar tothe configuration illustrated in FIG. 4.

[0098] In the first set of experiments, the base webs were wrappedaround 3 shear-inducing rolls at a pressure of 25 pounds per linearinch. The fabrics were wrapped around the shear-inducing rolls in anamount of about 45 0.

[0099] During the first set of tests, the diameter of the shear-inducingrolls was varied between 2 inches, 4.5 inches and 10.5 inches. Further,the amount of softwood fibers contained in the web was also varied(middle layer of the web) from 28% by weight to 31% by weight.

[0100] Linear regression mathematical models were developed for strengthand softness in order to create strength and softness curves. Theresults of the first set of experiments is illustrated in FIG. 8. Forpurposes of comparison, a control curve was also created. The controlcurve was produced by calendering the base web at a pressure of 150pounds per linear inch, instead of subjecting the web to theshear-inducing rolls and then estimating a curve.

[0101] During these tests, softness was determined using an in handranking test (IHR). Panelists received 6 samples and were asked to rankthem for softness based upon subjective criteria. Specifically, thepanelists received different sets of samples several times. Each samplewas coded. Replicates were compared in order to estimate error. Thepanelists response data was modeled with Logistic Regression todetermine paired scores and log odds.

[0102] Strength was determined using a geometric mean tensile strengthtest (GMT). In particular, the tensile strength of samples wasdetermined in the machine direction and in the cross machine direction.The size of the samples tested were 3 inches in width unless indicatedto the contrary. During the test, each end of a sample was placed in anopposing clamp. The clamps held the material in the same plane and movedapart at a ten inch per minute rate of extension. The clamps moved apartuntil breakage occurred in order to measure the tensile strength of thesample. The geometric mean tensile strength is then calculated by takingthe square root of the machine-direction tensile strength of the samplemultiplied by the cross-direction tensile strength of the sample.

[0103] Tensile strength tests can be performed, for instance, on theSintech 2 tester, available from the Sintech Corporation of Cary, N.C.,the Instron Model TM available from the Instron Corporation of Canton,Mass., a Thwing-Albert Model INTELLECT II available from theThwing-Albert Instrument Company of Philadelphia, Pa., or SYNERGY 100available from MTS Systems, Corp. located in Eden Prairie, Minn. Resultsare reported in grams or in grams per inch width of sample.

[0104] In order to construct the graph illustrated in FIG. 8, linearregression models were calculated for strength and softness.Specifically, a Y=f (x) model for strength and softness was created. Aspreadsheet was created listing softness and strength values as thepercent of softwood in the web varied for each of the three rolldiameters of interest (2 inches, 4.5 inches, and 10.5 inches). For eachpoint in the spreadsheet a value for strength and softness wascalculated from the regression models. The graph shown in FIG. 8 wasthen created plotting softness on one axis and strength on the otheraxis grouped by the roll diameter.

[0105] As shown in FIG. 8 the process of the present invention shiftsthe strength/softness curve towards creating softer and stronger webs.Further, decreasing the shear-inducing roll diameter further increasesthe softness of the webs at a given strength.

[0106] During the experiments, it was also noticed that between 5% to15% caliper reduction was obtained, without positively or negativelyaffecting any other product attributes.

[0107] Using the mathematical models, another set of curves wasgenerated from another set of experiments. Specifically, in this set ofexperiments, only a single shear-inducing roll was used. The results areshown in FIG. 9.

[0108] As shown, a decrease in the diameter of the shear-inducing rollhad a greater impact upon the base webs in comparison to the control.

EXAMPLE 2

[0109] In this experiment, a nonwoven web was formed, placed between twoconveyors, and then guided around three small rolls. The web producedwas a stratified web including three layers. The center layer was 100%softwood and made up approximately 34% by weight of the total web. Thetwo outer layers were each approximately 33% by weight of the web andwere a 3:1 mixture (by weight) of eucalyptus fibers and broke. Inaddition, 5.1 kg/metric ton of total fiber furnish of PROSOFT TQ 1003debonder obtained from Hercules, Inc. was added to the outer layers ofthe web and 6.0 kg/metric ton of total fiber furnish of HERCOBOND wetstrength agent obtained from Hercules, Inc. was added to the centerlayer. Additionally, the softwood fibers were refined at a load of 2.75HP-day/metric ton.

[0110] The web was produced using a through-air dryer apparatus similarto the system illustrated in FIG. 3. The through-air drying apparatusincluded a Voith t1205-1 fabric for carrying the web through theapparatus. The web entered the through-air drying apparatus at aconsistency of approximately 29%, and left the through-air dryingsection of the process at a consistency of about 98%.

[0111] Leaving the through-air drying apparatus, the web had a caliperof approximately 32 to 36 mils. Caliper of the web was determined by useof an EMVECO 200A Tissue Caliper Tester. Throughout the experimentalprocedures, caliper was measured at a load of about 2.00 kPa over anarea of about 2500 mm².

[0112] Following the through-air drying apparatus, the web was placedbetween two conveyors and fed around a set of shear-inducing rolls. Oneconveyor was a style 960 fabric available from the Asten JohnsonCorporation. This fabric was travelling at approximately 1600 ft/min.The other conveyor was a style 866B fabric, also available from theAsten Johnson Corporation. Due to the speed differential created by thepresence of the shear-inducing rolls, this second fabric was travellingat approximately 1615 ft/min. Both conveyors were at fabric tensions ofabout 30-35 pounds per linear inch.

[0113] The web and the two conveyors traveled together over threeshear-inducing rolls, each of which had a 2.25″ diameter the total wrapangle around the three rolls was about 128°. The individual wrap anglefor each roll was, 32°, 60 °, and 36°, sequentially. The web left theshear-inducing rolls with a caliper of about 20-24 mils.

[0114] After the shear-inducing section of the process, the web wascalendered in a rubber/steel configuration with a rubber roll coveringof about 40 P&J hardness and a nip load of about 15 pli.

[0115] The web produced according to the above process was then testedfor void volume, geometric mean tensile strength as described in EXAMPLE1, caliper, and fuzz-on-edge.

[0116] Void volume of the resultant sheet was determined according tothe following void-volume test. First, the sheet was saturated with anon-polar liquid and the volume of liquid absorbed was measured. Thevolume of liquid absorbed is equivalent to the void volume within thesheet structure. The void volume is expressed as grams of liquidabsorbed per gram of fiber in the sheet.

[0117] More specifically, the test includes the following steps. Foreach single-ply sheet sample to be tested, sheets are selected and a 1inch×1 inch square (1 inch in the machine direction and 1 inch in thecross machine direction) is cut out. The dry weight of each testspecimen is weighed and recorded to the nearest 0.0001 gram.

[0118] The specimen is placed in a dish containing POROFIL™ pore wettingliquid of sufficient depth and quantity to allow the specimen to floatfreely following absorption of the liquid. (POROFIL™ liquid, having aspecific gravity of 1.875 grams per cubic centimeter, available fromCoulter Electronics Ltd., Northwell Drive, Luton, Beds., England; PartNo. 9902458.) After 10 seconds, the specimen is held at the very edge(1-2 millimeters in) of one corner with tweezers and removed from theliquid. The specimen is held with that corner uppermost and excessliquid is allowed to drip for 30 seconds. The lower corner of thespecimen is lightly dabbed (less than ½ second contact) with #4 filterpaper (Whatman Ltd., Maidstone, England) in order to remove any excessof the last partial drop. The specimen is immediately weighed, within 10seconds. The weight is recorded to the nearest 0.0001 gram. The voidvolume for each specimen, expressed as grams of POROFIL per gram offiber, is calculated as follows:

Void volume=[(W ₂ −W ₁)/W _(1],)

[0119] wherein

[0120] W₁=dry weight of the specimen, in grams, and

[0121] W₂=wet weight of the specimen, in grams.

[0122] The void volume for all eight individual specimens is determinedas described above and the average of the eight specimens is the voidvolume for the sample.

[0123] The fuzz-on-edge test is an image analysis test. The imageanalysis data are taken from two glass plates made into one fixture.Each plate has a sample folded over the edge with the sample folded inthe CD direction and placed over the glass plate. The edge is beveled to{fraction (1/16)}″ thickness.

[0124] Referring to FIG. 10, one embodiment of a fixture that can beused in conducting the fuzz-on-edge test is shown. As illustrated, thefixture includes a first glass plate 202 and a second glass plate 204.Each of the glass plates have a thickness of ¼ inch. Further, glassplate 202 includes a beveled edge 206 and glass plate 204 includes abeveled edge 208. Each beveled edge has a thickness of {fraction (1/16)}inch. In this embodiment, the glass plates are maintained in position bya pair of U-shaped brackets 210 and 212. Brackets 210 and 212 can bemade from, for instance, ¾ inch finished plywood.

[0125] During testing, samples are placed over the beveled edges 206 and208. Multiple images of the folded edges are then taken along the edgeas shown at 214. Thirty (30) fields of view are examined on each foldededge to give a total of sixty (60) fields of view. Each view has “PR/EL”measured before and after removal of protruding fibers. “PR/EL” isperimeter per edge-length examined in each field-of-view. FIG. 11illustrates the measurement taken. As shown, “PR” is the perimeteraround the protruding fibers while “EL” is the length of the measuredsample. The PR/EL valves are averaged and assembled into a histogram asan output page. This analysis is completed and the data is obtainedusing the QUANTIMET 970 Image Analysis System obtained from Leica Corp.of Deerfield, Ill. The QUIPS routine for performing this work, FUZZ10,is as follows:

[0126] Cambridge Instruments QUANTIMET 970 QUIPS/MX: VO8.02 USER:ROUTINE: FUZZIO DATE: 8-MAY-81 RUN: 0 SPECIMEN:

[0127] NAME=FUZZB

[0128] DOES=PR/EL ON TISSUES; GETS HISTOGRAM

[0129] AUTH=B.E. KRESSNER

[0130] DATE=10 DEC 97

[0131] COND—

[0132] MACROVIEWER; DCI 12×12; FOLLIES PINK

[0133] FILTER; 3×3 MASK 60 MM MICRO-NIKKO,F/4; 20

[0134] MM EXTENSION TUBES; 2 PLATE (GLASS)

[0135] FIXTURE MICRO-NIKKOR AT FULL EXTENSION

[0136] FOR MAX MAG!!!!

[0137] ROTATE CAM 90 deg SO THAT IMAGE ON RIGHT SIDE!!

[0138] ALLOWS TYPICAL PHOTO

[0139] Enter specimen identity

[0140] Scanner (No. 1 Chalnicon LV=0.00 SENS=2.36 PAUSE)

[0141] Load Shading Corrector ( pattern—FUZZ7)

[0142] Calibrate User Specified (Cal Value—9.709 microns per pixel)SUBRTN STANDARD TOTPREL := 0. TOTFIELDS := 0. PHOTO := 0. MEAN := 0. IfPHOTO = 1. then Pause Message WANT TYPICAL PHOTO (1 = YES; 0 = NO)?Input PHOTO Endif If PHOTO = 1. then Pause Message INPUT MEAN VALUE FORPR/EL Input MEAN Endif For SAMPLE = 1 to 2 If SAMPLE = 1. then STAGEX :=36000. STAGEY := 144000. Stage Move (STAGEX,STAGEY) Pause Message pleaseposition fixture Pause STAGEX := 120000. STAGEY := 144000. Stage Move(STAGEX,STAGEY) Pause Message please focus Detect 2D  (Darker than 54,Delin PAUSE) STAGEX := 36000. STAGEY := 144000. Endif If SAMPLE = 2.then STAGEX := 120000. STAGEY := 44000. Stage Move (STAGEX,STAGEY) PauseMessage please focus Detect 2D (Darker than 54, Delin) STAGEX := 36000.STAGEY := 44000. Endif Stage Move ( STAGEX,STAGEY) Stage Scan ( X Y scanorigin STAGEX STAGEY field size 6410.0 78000.0 no of fields 30 1 ) ForFIELD If TOTFIELDS = 30. then Scanner (No. 1 Chalnicon AUTO-SENSITIVITYLV= 0.01) Endif Live Frame is Standard Image Frame Image Frame isRectangle (X: 26, Y: 37, W: 823, H: 627, ) Scanner (No. 1 ChalniconAUTO-SENSITIVITY LV= 0.01 ) Image Frame is Rectangle (X: 48, Y: 37, W:803, H: 627, ) Detect 2D (Darker than 54, Delin) Amend (OPEN by 0 )Measure field - Parameters into array FIELD BEFORPERI := FIELD PERIMETERAmend (OPEN by 10) Measure field - Parameters into array FIELD AFTPERIM:= FIELD PERIMETER PROVEREL := ( ( BEFORPERI - AFTPERIM ) / (I.FRAME.H * CAL.CONST ) ) TOTPREL := TOTPREL + PROVEREL TOTFIELDS:=TOTFIELDS + 1. If PHOTO = 1. then If PROVEREL > ( 0.95000 * MEAN ) thenIf PROVEREL < (1.0500 * MEAN ) then Scanner (No. 1 ChalniconAUTO-SENSITIVITY LV= 0.01 PAUSE) Detect 2D (Darker than 53 and Lighterthan 10, Delin PAUSE) Endif Endif Endif Distribute COUNT vs PROVEREL(Units MM/MM ) into GRAPH from 0.00 to 5.00 into 20 bins, differentialStage Step Next FIELD Next Print “ ” Print “AVE PR-OVER-EL (UM/UM) =” ,TOTPREL / TOTFIELDS Print “ ” Print “TOTAL NUMBER OF FIELDS =” ,TOTFIELDS Print “ ” Print “FIELD HEIGHT (MM) =”,I.FRAME.H * CAL.CONST/1000 Print “ ” Print “ ” Print Distribution ( GRAPH, differential, barchart, scale = 0.00) For LOOPCOUNT = 1 to 26 Print “ ” Next END OFPROGRAM

[0143] The product sheet exhibited the following characteristics:

[0144] basis weight—31.4 gsm (bone dry)

[0145] geometric mean tensile strength—531 grams/3″ width (177 g/in)measured with a 2 inch gap between grips

[0146] caliper—0.0159 inches

[0147] void volume—12.0 g fluid/g fiber

[0148] Fuzz-on-Edge (FOE)—2.165 perimeter ratio/edge length

EXAMPLE 3

[0149] An uncreped through-air-dried web was made as described inExample 2, with the exception that the three shear-inducing rolls ofExample 2 were replaced with three 4.5″ diameter rolls and the totalwrap angle around the three rolls was about 90°. Additionally, the webwas calendered in a rubber/steel configuration with a rubber rollcovering of about 40 P&J hardness and a nip load of about 25 pli.

[0150] The product sheet exhibited the following characteristics:

[0151] basis weight—32.07 gsm (bone dry)

[0152] geometric mean tensile strength—621 grams/3″ width (207 g/in)measured with a 2 inch gap between grips

[0153] caliper—0.0180 inches

[0154] Fuzz-on-Edge (FOE)—2.357 perimeter ratio/edge length

EXAMPLE 4

[0155] An uncreped through-air-dried web was made as described inExample 2, with the exception that the three shear-inducing rolls ofExample 2 were replaced with three 4.5″ diameter rolls and the totalwrap angle around the three rolls was about 163°. Additionally, the webwas calendered in a rubber/steel configuration with a rubber rollcovering of about 40 P&J hardness and a nip load of about 25 pli.

[0156] The product sheet exhibited the following characteristics:

[0157] basis weight—31.80 gsm (bone dry)

[0158] geometric mean tensile strength—583 grams/3″ width (194 g/in)measured with a 2 inch gap between grips

[0159] caliper—0.0156 inches

[0160] Fuzz-on-edge (FOE)—2.548 perimeter ratio/edge length

EXAMPLE 5

[0161] An uncreped through-air-dried web was made as described inExample 2, with the exception that the three shear-inducing rolls ofexample 2 were replaced with three 4.5″ diameter rolls and the totalwrap angle around the three rolls was about 163°. Additionally, the webwas calendered in a rubber/steel configuration with a rubber rollcovering of about 40 P&J hardness and a nip load of about 0 pli.

[0162] The product sheet exhibited the following characteristics:

[0163] basis weight—32.14 gsm (bone dry)

[0164] geometric mean tensile strength—616 grams/3″ width (205 g/in)measured with a 2 inch gap between grips

[0165] caliper—0.0189 inches

[0166] Fuzz-on-edge (FOE)—2.726 perimeter ratio/edge length

EXAMPLE 6

[0167] An uncreped through-air-dried web was made as described inExample 2, with the exception that the three shear-inducing rolls ofexample 2 were replaced with one 4.5″ diameter roll and the total wrapangle around the roll was about 60°. Additionally, the web wascalendered in a rubber/steel configuration with a rubber roll coveringof about 40 P&J hardness and a nip load of about 100 pli.

[0168] The product sheet exhibited the following characteristics:

[0169] basis weight—32.39 gsm (bone dry)

[0170] geometric mean tensile strength—635 grams/3″ width (212 g/in)measured with a 2 inch gap between grips

[0171] caliper—0.0163 inches

[0172] Fuzz-on-edge (FOE)—2.332 perimeter ratio/edge length

[0173] These and other modifications and variations to the presentinvention may be practiced by those of ordinary skill in the art,without departing from the spirit and scope of the present invention,which is more particularly set forth in the appended claims. Inaddition, it should be understood that aspects of the variousembodiments may be interchanged both in whole or in part. Furthermore,those of ordinary skill in the art will appreciate that the foregoingdescription is by way of example only, and is not intended to limit theinvention so further described in such appended claims.

What is claimed is:
 1. A process for producing base webs comprising:forming a base web containing pulp fibers; placing said base web betweena first moving conveyor and a second moving conveyor; guiding said firstmoving conveyor and said second moving conveyor around at least oneshear-inducing element while said base web is positioned between saidconveyors, said first and second conveyors being sufficiently wrappedaround said at least one shear-inducing element so as to create shearforces that act upon the base web and increase the softness of the web.2. A process as defined in claim 1, wherein said shear-inducing elementcomprises a roll having a diameter of less than about 10 inches.
 3. Aprocess as defined in claim 1, wherein said first and second conveyorsare guided around a first support roll prior to said shear-inducingelement and around a second support roll after said shear-inducingelement, each of said first and second support rolls including a centerthat is located in a common plane, said shear-inducing element beingpositioned in between said first and said second support rolls andpositioned a preselected distance from said plane.
 4. A process asdefined in claim 1, wherein said first moving conveyor and said secondmoving conveyor are guided around at least two shear-inducing elements.5. A process as defined in claim 1, wherein said base web comprises astratified web.
 6. A process as defined in claim 1, wherein said baseweb is a stratified web including a middle layer positioned between afirst outer layer and a second outer layer, said first and second outerlayers having a greater tensile strength than said middle layer.
 7. Aprocess as defined in claim 1, wherein said base web is a stratified webincluding a middle layer positioned between a first outer layer and asecond outer layer, said middle layer having a tensile strength greaterthan said first and second outer layers.
 8. A process as defined inclaim 1, wherein said base web comprises a single ply web having a basisweight of at least 20 gsm.
 9. A process as defined in claim 1, whereinsaid base web when guided around said shear-inducing element has amoisture content of less than about 10% by weight.
 10. A process asdefined in claim 1, wherein said first moving conveyor and said secondmoving conveyor are under a tension of at least 5 pounds per linear inchwhen guided around said shear-inducing element.
 11. A process as definedin claim 1, wherein said first and second conveyors are wrapped aroundat least 3 shear-inducing elements.
 12. A process as defined in claim 1,wherein said first and second conveyors are wrapped around at least 5shear-inducing elements.
 13. A process as defined in claim 1, whereinsaid first and second conveyors are wrapped around said shear-inducingelement at least 30°.
 14. A process as defined in claim 1, wherein saidshear-inducing element has an effective diameter of less than about 7inches.
 15. A process as defined in claim 1, wherein said shear-inducingelement has an effective diameter of from about 2 inches to about 5inches.
 16. A process as defined in claim 1, wherein said first conveyorand said second conveyor are wrapped around said shear-inducing elementat least 50°.
 17. A paper product comprising: a nonwoven base web, saidbase web containing pulp fibers, said base web having a void volumegreater than 12 g/g.
 18. A paper product as defined in claim 17, whereinsaid base web has a basis weight of greater than 20 gsm.
 19. A paperproduct as defined in claim 17, wherein said base web has a basis weightof greater than 30 gsm.
 20. A paper product as defined in claim 17,wherein said paper product comprises a single-ply product.
 21. A paperproduct as defined in claim 17, wherein said base web has a geometricmean tensile strength of greater than about 170 g/in.
 22. A paperproduct as defined in claim 17, wherein said base web has a geometricmean tensile strength of greater than about 200 g/in.
 23. A paperproduct as defined in claim 17, wherein said base web has a fuzz-on-edgeof greater than about 2.2 mm/mm.
 24. A paper product as defined in claim17, wherein said base web has a fuzz-on-edge of greater than about 2.5mm/mm.
 25. A paper product as defined in claim 17, wherein said base webhas a basis weight of greater than about 25 gsm, has a geometric meantensile strength of greater than about 170 g/in, and has a fuzz-on-edgeof greater than about 2.2 mm/mm.
 26. A paper product as defined in claim17, wherein said base web comprises an uncreped, through-air-dried web.27. A paper product comprising: a nonwoven base web, said base webcontaining pulp fibers, said base web having a fuzz-on-edge of greaterthan about 2.2 mm/mm.
 28. A paper product as defined in claim 27,wherein said base web has a basis weight of greater than 20 gsm.
 29. Apaper product as defined in claim 28, wherein said base web has a voidvolume greater than 12 g/g.
 30. A paper product as defined in claim 27,wherein said base web has a fuzz-on-edge of greater than about 2.5mm/mm.
 31. A paper product as defined in claim 27, wherein said paperproduct comprises a single-ply product.
 32. A paper product as definedin claim 27, wherein said base web has a geometric mean tensile strengthof greater than about 170 g/in.
 33. A paper product as defined in claim27, wherein said base web has a geometric mean tensile strength ofgreater than about 200 g/in.
 34. A paper product as defined in claim 27,wherein said base web comprises an uncreped, through-air-dried web. 35.A process for producing base webs comprising: forming a base webcontaining pulp fibers; and subjecting said base web to a shearing forcein an amount sufficient to increase the void volume of said base web,said base web having a void volume of greater than 12 g/g.
 36. A processas defined in claim 35, wherein said base web is subjected to saidshearing force in an amount sufficient to also increase the fuzz-on-edgeproperties of the web, said base web having a fuzz-on-edge in an amountof at least 2.2 mm/mm.
 37. A process as defined in claim 35, whereinsaid base web has a moisture content of less than about 10% by weightwhen subjected to said shearing force.
 38. A process as defined in claim35, wherein said base web comprises a single-ply web, said base webhaving a basis weight of at least about 20 gsm.
 39. A process as definedin claim 35, wherein said base web is subjected to said shearing forceby placing said base web in between a first moving conveyor and a secondmoving conveyor, and guiding said first moving conveyor and said secondmoving conveyor around a shear-inducing roll while said base web ispositioned between said conveyors.
 40. A process as defined in claim 39,wherein said first and second conveyors are wrapped around saidshear-inducing roll at least 50°.